Arrangement for placement and alignment of opto-electronic components

ABSTRACT

An arrangement for providing passive alignment of optical components on a common substrate uses a set of reference cavities, where each optical device is positioned within a separate reference cavity. The reference cavities are formed to have a predetermined depth, with perimeters slightly larger than the footprint of their associated optical components. The reference cavity includes at least one right-angle corner that is used as a registration corner against which a right-angle corner of an associated optical component is positioned. The placement of each optical component in its own reference cavity allows for passive optical alignment to be achieved by placing each component against its predefined registration corner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/558,006 filed Nov. 10, 2011 and U.S. Provisional Application No.61/558,788 filed Nov. 11, 2011, both of which are herein incorporated byreference.

TECHNICAL FIELD

The present disclosure relates generally to opto-electronic assemblies,particularly to the utilization of precision-created reference cavitiesfor providing passive alignment between optical components of anopto-electronic assembly.

BACKGROUND

Many types of opto-electronic modules comprise a number of separateoptical and electrical components that require precise placementrelative to one another. A silicon (or glass) carrier substrate(sometimes referred to as an interposer) is generally used as a supportstructure to fix the location of the components and may, at times, alsoprovide the desired electrical or optical signal paths between selectedcomponents. In other arrangements, the optical and electrical componentsmay be directly placed on and within a silicon surface layer of asilicon-on-insulator (SOI)-based optical platform. Regardless of thestructure of the support arrangement, optical alignment between variousoptical components is required to ensure that the integrity of theoptical signal path is maintained.

Active alignment processes generally require the use of visual systemsin combination with micro-positioning arrangements to adjust theposition of a first optical component with respect to another opticalcomponent. These active alignment arrangements are generally slow andexpensive, impacting throughput and cycle time in assembly operations.In contrast to active alignment, “passive” optical alignmentarrangements may be utilized, which rely on matching and matingalignment fiducials formed on both the substrate and each opticalcomponent. As one drawback, passive alignment arrangements add cost andcomplexity to the fabrication of the individual components by requiringthe additional steps associated with forming the fiducials on eachoptical component. Moreover, these opto-electronic assemblies aretypically built as individual units and, as a result, the need toperform optical alignment (active or passive) on a unit-by-unit basisbecomes expensive and time-consuming.

Indeed, as the demand for opto-electronic modules continues to increase,the individual unit assembly approach has become problematic. Waferlevel packaging is considered to be a more efficient and cost-effectiveapproach, with one exemplary arrangement of wafer level packagingdisclosed in our co-pending application Ser. No. 13/463,408, filed May3, 2012 and herein incorporated by reference.

In our co-pending application, a silicon wafer is utilized as a“platform” (i.e. interposer or carrier) upon which all of the componentsfor a multiple number of opto-electronic modules are mounted orintegrated, with the top surface of the silicon interposer used as areference plane for defining the optical signal path for opticalalignment purposes. The use of a single silicon wafer as a platform fora large number of separate modules allows for a wafer level assemblyprocess to efficiently assemble a large number of modules in arelatively short period of time.

While the use of wafer level assembly does improve the efficiency of thefabrication process, the use of an active alignment process remains adrawback in terms of its complexity and low throughput. As the size andcomplexity of opto-electronic assemblies continues to increase, theability to find locations on both the substrate and the opticalcomponents to create alignment fiducials for passive alignmentalternatives becomes increasingly difficult.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this disclosure, illustrate various embodiments of the presentinvention. In the drawings:

FIG. 1 is an isometric view of an opto-electronic module assembly,illustrating the placement of optical components in an alignedconfiguration, as well as an exemplary optical signal path between thealigned components;

FIG. 2 is an isometric view of the substrate of FIG. 1, in itsunpopulated form, showing a plurality of reference cavities used forplacement and passive alignment of optical components in accordance withthe present invention;

FIGS. 3-5 illustrate an exemplary set of processing steps used to createreference cavities in a passivation layer overlying a substrate inaccordance with one embodiment of the present invention, with FIGS. 3(a), 4(a) and 5(a) showing top views of the optical substrate and FIGS.3( b), 4(b) and 5(b) showing cut-away side views of the samearrangement, with regions of the passivation layer removed to form thereference cavities;

FIG. 6 illustrates an alternative arrangement to the configuration ofFIGS. 3-5, with a plurality of reference cavities directly etched in acommon silicon substrate of an SOI-based arrangement used to support aplurality of optical components, where FIG. 6( a) is a top view of theSOI-based arrangement and FIG. 6( b) is a side view of the SOI-basedarrangement, taken along line 6-6 of FIG. 6( a);

FIG. 7 shows another embodiment of the present invention, in this caseincluding a plurality of grooves formed within at least one of thereference cavities, the grooves used to direct the placement of adhesivematerial and allow for the creation of thin bond lines, as preferred,with FIG. 7( a) being a top view of an exemplary substrate, including aset of reference cavities, FIG. 7( b) being an enlarged view of onecavity, showing the formation of a plurality of grooves on the floor ofthe cavity, and FIG. 7( c) being a cut-away side view of the enlargementof FIG. 7( b), taken along line 7-7, showing the grooves in a side view;and

FIG. 8 depicts yet another embodiment of the present invention, in thiscase including a plurality of ribs formed across the bottom surface ofat least one of the reference cavities, the ribs used as a standoff tocontrol the depth of the placement of an optical component with respectto the reference cavity, with FIG. 8( a) being a top view of anexemplary substrate including a reference cavity, FIG. 8( b) being acut-away side view, taken along line 8-8 and showing the plurality ofribs within the reference cavity, and FIG. 8( c) being a side viewillustrating the placement of an optical component on the ribs withinthe reference cavity.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

An opto-electronic assembly is provided comprising a substrate(generally of silicon or glass) for supporting a plurality ofinterconnected optical and electrical components. A reference cavity isformed through the surface of the substrate at each location where anoptical component is to be placed. Each reference cavity is formed tohave a depth no greater than about 30 microns, with a perimeter slightlylarger than the footprint of the associated optical component. Eachreference cavity includes at least one right-angle corner that is usedas a registration corner against which a right-angle corner of anassociated optical component is positioned. The placement of eachoptical component in its own reference cavity allows for passive opticalalignment to be achieved by placing each component against itspredefined registration corner. Conventional bonding techniques may beused to permanently each component in its precise location.Alternatively, an additional feature of the present invention includesthe formation of grooves (or ribs) within the “floor” of the referencecavities, with bonding material preferentially disposed within thegrooves (or between the ribs) to form thin bond lines.

Example Embodiments

The following detailed description refers to the accompanying drawings.Wherever possible, the same reference numbers are used in the drawingsand the following description to refer to the same or similar elements.While embodiments of the invention may be described, modifications,adaptations, and other implementations are possible. For example,substitutions, additions, or modifications may be made to the elementsillustrated in the drawings, and the methods described herein may bemodified by substituting, reordering, or adding stages to the disclosedmethods. Accordingly, the following detailed description does not limitthe invention. Instead, the proper scope of the invention is defined bythe appended claims.

FIG. 1 is an isometric view of an opto-electronic module assembly,illustrating the placement of optical components in an alignedconfiguration, as well as an exemplary optical signal path between thealigned components. As shown, a substrate 10 is used as a support memberto hold a plurality of separate optical components in an alignedconfiguration. In this particular arrangement, the assembly includes alaser diode 12 that is a source of a propagating optical signal. Amicrolens 14 is shown as placed in the optical output signal path fromthe laser diode 12. An optical isolator 16 is positioned beyond themicrolens 14 and is used to prevent reflected optical signals fromre-entering the laser diode 12. The signal exiting the optical isolator16 then passes through a microlens array 18 and enters a CMOS photonicchip 20.

Signal processing operations are performed on the optical signal withinthe photonic chip 20 (for example, modulation with a data signal),creating an output optical signal that will exit the photonic chip 20 asshown, pass again through the microlens array 18 and be coupled into anoptical coupling interface arrangement 30. In the particular embodimentshown in FIG. 1, the optical coupling interface arrangement 30 is shownin an exploded view and comprises a microlens array 32 and an associatedoptical fiber array 34, with the optical fiber array 34 supported on asubstrate 36. The optical coupling interface arrangement 30 is alsoshown as providing a signal path for an input (received) optical signalwhich propagates along one or more fibers of the optical fiber array 34.The input optical signal then passes through the microlens array 32 andis thereafter directed through a collimating lens 40 into an opticalreceiving component 42.

It is to be understood that this set of optical components is exemplaryonly, illustrating one particular arrangement where optical alignmentbetween various components is required. In general, any arrangement ofoptical components (passive and/or active) that are disposed on a commonsubstrate and need to arranged in an optically aligned configuration mayutilize the reference cavity passive alignment attributes of the presentinvention.

In following the optical signal path through the system shown in FIG. 1,it is obvious that optical alignment between the various opticalcomponents is important. For example, the output optical signal from thelaser diode 12 has a relatively small beam waist and needs to be alignedwithin a few microns of the focal point of the microlens 14. Opticalalignment also needs to be maintained, for example, along the signalpath through the isolator 16, the microlens array 18 into an opticalinput port (not shown) of the photonic chip 20. Heretofore, techniquesdescribed above (such as active alignment using a video system, orpassive alignment using mating fiducial features on the components andthe substrate) would be used to achieve optical alignment.

In accordance with the present invention, passive alignment betweenoptical components is achieved by utilizing reference cavities, formedwithin the top surface of a substrate supporting the optical components,with a separate reference cavity used to contain and properly locateeach optical component such that passive optical alignment between theoptical components is achieved. FIG. 2 is an isometric view of thesubstrate 10, in its unpopulated form, showing a plurality of referencecavities used for placement and passive alignment of optical componentsin accordance with the present invention.

In particular, FIG. 2 illustrates a plurality of separate referencecavities 50 that are formed through a top surface 11 of the substrate 10and used to provide passive optical alignment in accordance with thepresent invention. Various processes, as described hereinafter, may beused to form the reference cavities in predefined locations, to apredefined depth and having predefined x-y dimensions (the x-y planedefining the top surface 11 of the substrate 10). In comparison to priorart passive alignment schemes, the arrangement of the present inventiondoes not require the use of alignment fiducials and, therefore, does notrequire extra processing of the optical components to create a passivealignment structure. The elimination of alignment fiducials on thesubstrate is also beneficial in systems where extra space for suchelements is at a premium.

For the particular set of optical components shown in FIG. 1, thesubstrate 10 is processed to include a set of seven separate referencecavities: a laser reference cavity 52, a microlens reference cavity 54,an isolator reference cavity 56, a microlens array reference cavity 58,a photonic chip reference cavity 60, an optical interface connectorreference cavity 62 and a receiver lens array cavity 64. In theparticular arrangement as shown in FIG. 2, each reference cavityexhibits a rectangular perimeter (in the x-y plane of substrate 10),with a depth d sufficient to support the associated optical component.Each reference cavity is formed to comprise the same depth d, which isgenerally less than about 30 μm, and preferably on the order of 5-20 μm.

In comparing the optical components as shown in FIG. 1 with theirrespective reference cavities as shown in FIG. 2, each reference cavityis shown as including an x-y perimeter that essentially matches the“footprint” of its associated optical component (i.e., a squarecomponent such as the laser diode 12 has a square reference cavity 52, arectangular component such as the photonic chip 20 has a rectangularreference cavity 60). This configuration of matching perimeters is apreferred, but not mandatory, element of the inventive arrangement. Ingeneral, as long as each optical component includes at least oneright-angle corner, a reference cavity having a matching right-anglecorner may be used to fix (i.e., “register”) the location of the opticalcomponent with respect to the x-y plane of the optical substrate 10. Bypredefining the registration corners to be used for this purpose, theplurality of reference cavities 50 can be formed relative to one anothersuch that passive optical alignment occurs upon placement of the opticalcomponents in their respective reference cavities, with a predefinedcorner of each optical component positioned against a predefined cornerof its associated reference cavity.

It is to be understood that prior to placing the optical components intheir respective reference cavities, a bonding material (such as anepoxy, not shown) is injected into the cavity, whereupon it will becured after placement of the optical components, providing a permanentattachment of the optical component within its respective referencecavity.

FIGS. 3-5 illustrate an exemplary set of processing steps used to createreference cavities in a passivation layer overlying a substrate inaccordance with one embodiment of the present invention, with FIGS. 3(a), 4(a) and 5(a) showing top views of the optical substrate and FIGS.3( b), 4(b) and 5(b) showing cut-away side views of the samearrangement, with regions of the passivation layer removed to form thereference cavities.

In particular, FIG. 3( a) is a top view of an optical substrate 100,prior to the creation of any of the reference cavities, with FIG. 3( b)being a side view of the optical substrate 100, taken along line 3-3 ofFIG. 3( a). As evident in the view of FIG. 3( b), the optical substrate100 comprises a support layer 110, with a relatively thin passivationlayer 112 disposed over the support layer 110. In the particularembodiment associated with FIGS. 3-5, the reference cavities are formedby creating openings in passivation layer 112. The thickness t ofpassivation layer 112 thus defines the depth of the reference cavities.As stated above, a depth on the order of 5-20 μm is suitable for thepurposes of the present invention (although values less than or greaterthan this preferred range may also be used, as long as the opticalsignal path is not blocked when the optical components are placed intheir reference cavities).

In accordance with this embodiment of the present invention, which maytake the form of an interposer configuration used to support optical andelectronic devices within a larger package structure, various materialsmay be used to form both the support layer 110 and the passivation layer112. For example, the support layer 110 may be formed of a silicon orglass material, with the passivation layer 112 formed of a polymermaterial, such as polyimide, or any other suitable dielectric material(e.g., silicon dioxide).

FIG. 4 illustrates an exemplary set of three reference cavities asformed within the optical substrate 100. As shown in the top view ofFIG. 4( a), the arrangement is formed to include a square referencecavity 120, a rectangular reference cavity 122 and an “edge” rectangularreference cavity 124. These cavities are formed by removing the portionsof the passivation layer 112 contained in the defined regions. FIG. 4(b) is a cut-away side view of the arrangement of FIG. 4( a), taken alongline 4-4 of FIG. 4( a). Various techniques, well-known in the art, maybe used to precisely define the location and dimensions of each of thesereference cavities, as well as remove the portions of the passivationlayer 112 in each reference cavity region. For example, conventionalphotolithographic techniques used in standard CMOS processing may beused to pattern the passivation layer 112 to define the x-y perimeter ofeach reference cavity and then remove selected portions of thepassivation material using an etching process. By knowing a set ofdefined locations for the optical components as determined to provideoptical alignment, the locations of their respective reference cavitieson the optical substrate can be defined. Those skilled in the art willrecognize that a myriad of techniques are available to create thesecavities with the desired properties.

As shown, each reference cavity includes at least one right-angle cornerthat is used as a registration corner location for precisely aligning aplaced optical component with respect to the optical substrate.Referring to FIG. 4( a), the reference cavity 120 is defined as having aregistration corner A, the reference cavity 122 is defined as having aregistration corner B and the reference cavity 124 is defined as havinga registration corner C. Each cavity is also slightly larger than thefootprint of the optical component it is to support so that the opticalcomponent may be placed in its cavity and then moved to physicallycontact the pair of sidewalls forming the registration corner of thereference cavity. For the purposes of the present invention, “slightlylarger” is deemed to mean having a length and width of between 1-5microns greater than the length and width of the associated opticalcomponent. Hereafter, these “slightly larger” length and width (x and y)dimensions of the reference cavity will be defined as creating an“oversized” reference cavity.

Once the oversized reference cavities are formed, an adhesive material(such as an appropriate solder or bonding material, not shown) isdisposed in each cavity and then the optical components are placed intheir respective reference cavities. This step is shown in FIG. 5, whereFIG. 5( a) is a top view, showing a first optical component 121 placedin the square reference cavity 120, a second optical component 123placed in the rectangular reference cavity 122, and a third opticalcomponent 125 placed in the edge rectangular cavity 124. In accordancewith the present invention, the respective reference corners of theseoptical components are placed against registration corners A, B and C oftheir respective cavities. By virtue of fixing the x-y location of eachof these optical components, passive optical alignment between theoptical components is achieved and the integrity of an optical signalpath between each component will be maintained.

The relative sizes of the reference cavities with respect to theiroptical components is shown in FIGS. 5( a) and (b), which demonstratesthe oversized nature of the reference cavities. While not extreme, a gapis clearly evident between an edge E of the reference cavity 124 andedge e of the optical component 125. In each case, it is clear thatregistration between a defined registration corner of a reference cavityand a corner of an associated optical component is provided, creatingpassive alignment between the optical components in accordance with thepresent invention.

The exemplary process as outlined in FIGS. 3-5 is based upon the use ofa substrate in the form of a two-layer combination of a support layerand a passivation layer. This arrangement may typically be found in theformation of an interposer (or carrier) element of an opto-electronicassembly. As mentioned above, it is also possible to form referencecavities of the present invention directly within a silicon surfacelayer of an SOT-based optical assembly. FIG. 6 illustrates analternative arrangement to the configuration of FIGS. 3-5, with aplurality of reference cavities directly etched in a common siliconsubstrate of an SOI-based arrangement used to support a plurality ofoptical components, where FIG. 6( a) is a top view of the SOI-basedarrangement and FIG. 6( b) is a side view of the SOI-based arrangement,taken along line 6-6 of FIG. 6( a).

In particular, FIG. 6 illustrates an SOI-based embodiment of the presentinvention, where a plurality of reference cavities is formed within asilicon surface layer 200 of an SOI-based arrangement 210. FIG. 6( a)shows a set of three reference cavities 300, 310 and 320 as formed inpredefined locations on the silicon surface layer 200. In the side viewof FIG. 6(b), the reference cavity 320 is shown as formed through thedepth of the silicon surface layer 200. A dielectric layer 214 (alsoreferred to in the art as buried oxide layer) and a silicon substrate216 are shown as completing the defined SOI-based structure 210. In thiscase, a deep reactive ion etch (deep RIE) process can be used to formthe set of reference cavities 300, 310 and 320. Other well-known typesof silicon processing may be used, as described above, to define theprecise locations and dimensions of each of these reference cavities, aswell as form the cavities to create the necessary right-angle corner(s).

Once all of the optical components have been placed against theirassociated registration corners within the reference cavities, a singlebonding operation may be performed to permanently attach the opticalcomponents to their locations. In some cases, thin bond lines are formedalong the bottom surface of each optical component, as well as on the“floor” of each reference cavity. In some cases, bonding can beperformed by using an adhesive filled with a low filler content andfiller particles having a variation of size within a desired bond linelimit (e.g., 0.1 μm). The latter approach requires dispensing a smallvolume of multiple dots within each reference cavity.

FIG. 7 shows another embodiment of the present invention, in this caseincluding a plurality of grooves formed within at least one of thereference cavities, the grooves used to direct the placement of adhesivematerial and allow for the creation of thin bond lines, as preferred,with FIG. 7( a) being a top view of an exemplary substrate, including aset of reference cavities, FIG. 7( b) being an enlarged view of onecavity, showing the formation of a plurality of grooves on the floor ofthe cavity, and FIG. 7( c) being a cut-away side view of the enlargementof FIG. 7( b) taken along line 7-7, showing the grooves in a side view.It is to be understood that not all of the cavities need to be formed toinclude these bonding grooves; rather, the inclusion of shallow groovesis considered to be a design feature that may be used at the discretionof the individual. FIG. 7( a) is a top view of the same arrangement asshown in FIG. 5( b), showing the substrate 100 and the set of threereference cavities 120, 122 and 124. FIG. 7( b) is an enlargement of thereference cavity 122, showing the formation of a plurality of grooves400 within a bottom surface 410 of the reference cavity 122. FIG. 7( c)is a cut-away side view of the reference cavity 122, showing thelocation of the plurality of grooves 400. These shallow grooves are usedin accordance with the present invention to hold an adhesive material,thus preventing the adhesive lines from having a variation in thicknessand/or placement, as was problematic with the prior art.

The grooves 400 may be V-shaped, squared, rectangular, U-shaped, or anydesired geometry, with a depth ranging from, for example, 1 μm to 10 μm,and widths also ranging from 1 μm to 10 μm. It is been determined thatthe use of these adhesive grooves 400 within reference cavities willassist in achieving bond line thickness variation within 0.1 μm acrossthe component dimension. Additionally, the use of the grooves will helpin achieving uniform placement of the adhesive across the dimension ofthe cavity, improving the quality of the adhesion between an insertedoptical component and the substrate.

Instead of forming grooves within the bottom of the reference cavities,it is also possible to include a plurality of ribs in the floor of areference cavity, which will serve the same purpose of guiding theadhesive material into the channels between the ribs. FIG. 8 depicts yetanother embodiment of the present invention, in this case including aplurality of ribs formed across the bottom surface of at least one ofthe reference cavities, the ribs used as a standoff to control the depthof the placement of an optical component with respect to the referencecavity, with FIG. 8( a) being a top view of an exemplary substrateincluding a reference cavity, FIG. 8( b) being a cut-away side view,taken along line 8-8 and showing the plurality of ribs within thereference cavity, and FIG. 8( c) being a side view illustrating theplacement of an optical component on the ribs within the referencecavity.

In particular, FIG. 8( a) is a top view of a substrate 500 formed toinclude a reference cavity 510. FIG. 8( b) is a cut-away side view takenalong line 8-8 of the view of FIG. 8( a), illustrating the inclusion ofa plurality of ribs 520 disposed along a bottom surface 511 of thereference cavity 510. The plurality of ribs 520 functions in a similarmanner to the plurality of grooves 400 in terms of providing flowchannels for directing the adhesive material to follow, forming aplurality of defined bond lines.

The plurality of ribs 520 additionally forms a standoff arrangementwithin the reference cavity 520, providing an additional degree ofcontrol of the depth of an associated optical component within itsassociated reference cavity. This aspect is illustrated in FIG. 8( c),which shows an exemplary optical component 550 placed within thereference cavity 510 so as to rest upon the plurality of ribs 520.Adhesive material 540 is disposed in the channels between the adjacentribs 520 and is used to permanently bond the optical component 550 inplace. By controlling the height of ribs 520, the height h of theoptical component 550 with respect to a top surface 501 of substrate 500is controlled.

While the invention has been described in terms of differentembodiments, those skilled in the art will recognize that the inventioncan be practiced with various modifications that are considered to fallwithin the spirit and scope of the invention as best defined by theclaims appended hereto. Furthermore, while the specification has beendescribed in language specific to structural features and/ormethodological acts, the claims are not limited to the features or actsdescribed above. Rather, the specific features and acts described aboveare disclosed as examples for embodiments of the invention.

What is claimed is:
 1. An optical assembly, comprising: a plurality ofoptical components configured to form an optical pathway; and a commonsubstrate, including: a top surface within a geometric plane comprisinga plurality of openings; and a plurality of internal surfaces forming aplurality of cavities extending into the common substrate from theplurality of openings, and the plurality of cavities configured toreceive respective ones of a plurality of optical components in aone-to-one relationship, wherein at least a portion of the plurality ofinternal surfaces form right-angle registration corners for each of theplurality of cavities, the right-angle registration corners areconfigured to abut against respective ones of the plurality of opticalcomponents, wherein the plurality of internal surfaces are disposed atpredefined locations within the common substrate such that passiveoptical alignment for the optical pathway between the plurality ofoptical components is provided upon placement of the plurality ofoptical components in the plurality of cavities with corners of theplurality of optical components abutting against respective ones of theright-angle registration corners, and wherein the optical pathway isconfigured to be disposed on an opposite side of the geometric planefrom the plurality of cavities.
 2. The optical assembly of claim 1,wherein each of the plurality of cavities includes a depth which is thesame or substantially the same depth.
 3. The optical assembly of claim2, wherein the depth is less than thirty microns to avoid the opticalpath from being incident upon the plurality of internal surfaces.
 4. Theoptical assembly of claim 3, wherein the same depth is in a range fromfive microns to twenty microns.
 5. The optical assembly of claim 1,wherein each one of the plurality of cavities exhibits a perimetersimilar in shape to a perimeter of the respective one of the pluralityof optical components.
 6. The optical assembly of claim 5, wherein eachone of the perimeters of the plurality of cavities is oversized withrespect to the perimeter of the respective one of the plurality ofoptical components.
 7. The optical assembly of claim 6, wherein theperimeters of the plurality of cavities are oversized relative to therespective ones of the plurality of optical components by an amount in arange from one to five microns in each dimension of the perimeters ofthe plurality of cavities.
 8. The optical assembly of claim 1, whereinthe common substrate comprises a two-layer structure including a supportlayer and a passivation layer, and each of the plurality of cavitiesextends through the passivation layer.
 9. The optical assembly of claim8, wherein the support layer comprises at least one of silicon andglass.
 10. The optical assembly of claim 8, wherein the passivationlayer comprises a polymer material.
 11. The optical assembly of claim10, wherein the polymer material comprises polyimide.
 12. The opticalassembly of claim 8, wherein the passivation layer comprises adielectric material.
 13. The optical assembly of claim 12, wherein thedielectric material comprises silicon dioxide.
 14. The optical assemblyof claim 1, wherein the common substrate comprises a silicon layer of asilicon-on-insulator (SOI)-based optical arrangement.
 15. The opticalassembly of claim 1, wherein the plurality of internal surfaces includea plurality of attachment surfaces, at least one of the plurality ofattachment surfaces includes grooves which are disposed in at least oneof the plurality of cavities, the grooves are configured to direct adisposition of adhesive material used for attaching at least one ofplurality of optical components to the respective at least one of theplurality of attachment surfaces.
 16. An arrangement for providingpassive optical alignment between a plurality of optical componentsdisposed on a common substrate, the arrangement comprising: the commonsubstrate, including: a top surface comprising a plurality of openings;and a plurality of internal surfaces forming a plurality of cavitiesextending into the common substrate from the plurality of openings, andthe plurality of cavities configured to receive respective ones of theplurality of optical components in a one-to-one relationship, wherein atleast a portion of the plurality of internal surfaces form right-angleregistration corners for each of the plurality of cavities, theright-angle registration corners are configured to abut againstrespective ones of the plurality of optical components, wherein theplurality of internal surfaces are disposed at predefined locationswithin the common substrate such that the passive optical alignment forthe optical pathway between the plurality of optical components isprovided upon placement of the plurality of optical components in theplurality of cavities with corners of the plurality of opticalcomponents abutting against respective ones of the right-angleregistration corners, wherein the plurality of internal surfaces includea plurality of attachment surfaces, at least one of the plurality ofattachment surfaces includes ribs which are disposed in at least one ofthe plurality of cavities, the ribs are configured to direct adisposition of adhesive material between the ribs, the ribs forming astandoff defining a depth of placement of an associated one of theplurality of optical components within the at least one of the pluralityof cavities.
 17. A method, comprising: defining a plurality of locationsof a plurality of optical components on a top surface of a commonsubstrate, the top surface contained within a geometric plane;patterning the top surface of the common substrate based on the definedplurality of locations to define a length dimension and a widthdimension of each of a plurality of cavities; removing a portion of thecommon substrate from each of the defined plurality of locations tocreate a plurality of internal surfaces forming the plurality ofcavities, at least a portion of the plurality of internal surfaces formright-angle registration corners which are associated with each of theplurality of cavities; positioning each of the plurality of opticalcomponents at least partially within a respective one of the pluralityof cavities such that a single corner of each of the plurality ofoptical components abuts against a respective one of the right-angleregistration corners to provide passive optical alignment for an opticalpathway between the plurality of optical components, the optical pathwayis disposed on an opposite side of the geometric plane from theplurality of cavities; and bonding the plurality of optical componentsin the defined plurality of locations to the plurality of internalsurfaces and at least partially within each of the plurality ofcavities.
 18. The method of claim 17, wherein the removing comprises anetching process to remove the portion of the common substrate.
 19. Themethod of claim 17, wherein the defining and the patterning areperformed upon the top surface which is part of a passivation layer ofthe common substrate, wherein the passivation layer overlays a siliconsupport substrate of the common substrate, and the removing includesremoving portions of the passivation layer to create the plurality ofcavities.
 20. The method of claim 17, wherein the removing comprisesremoving the portion of the common substrate through the top surfacewith deep reactive ion etching (deep RIE) to create the plurality ofinternal surfaces, and the portion includes a silicon surface layer ofan SOI-based arrangement, and the top surface is included as part of thesilicon surface layer.